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What is UTXO?

UTXO (Unspent Transaction Output) is how Bitcoin tracks ownership. Your BTC balance is the sum of all unspent outputs you’ve received. When you send BTC, you spend existing UTXOs and create new ones. Example: You receive 1 BTC from Alice and 0.8 BTC from Bob. Your wallet now has:
  • UTXO1: 1 BTC
  • UTXO2: 0.8 BTC
To send 0.5 BTC, you could spend either UTXO and receive change. To send 1.2 BTC, you’d spend both UTXOs and receive 0.6 BTC change (minus fees).

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Insufficient UTXOs

If your available UTXOs can’t cover the transaction plus fees, you’ll see a “UTXO Insufficient” error. Either wait for pending transactions to confirm or add funds from another address.

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Network Congestion

Bitcoin blocks have limited capacity. When transaction volume exceeds this limit, the network becomes congested and confirmations slow down.

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Avoid Congestion

StrategyDescription
Set appropriate feesHigher fees incentivize miners to prioritize your transaction
Use batch paymentsCombine multiple transfers into one transaction (learn more)
Time your transactionsAvoid peak congestion periods when possible